How to buy letter credits?

From the Subscription Section:

1. Click the grey icon in the top right corner of your map view.

2. Select 'Subscription' from the dropdown menu.

3. Under 'Title Credits,' click 'Buy Credit' and follow the instructions.

From a Mailshot:

1. At the final stage of creating your mailshot (Summary and Send), click on 'Top up your credit.'

2. Select the amount of credit you wish to purchase.

3. Follow the on-screen instructions to complete the transaction.